Loose-coupled tuning-coil.



1L0. GOWING 62; M. G. SPENCER.- LOOSE COUPLED TUNING COIL. APPLICATION FILED JUNE 31,1912.

Patented Dec. 30,1913. i fll WITNESSES:

' mun/mks: I $246.5 6 503a?? FM. W; f Z

' Arm/Mrs To all whom it may concern:

Amuse GOWING AND MILLARD COLE SPENCER, OF WORCESTER, MASSA- CHUSETTS.

. LOOSE-COUPLED TUiNING-GOIL.

Specification otjLetters Patent.

Patented Dec. 30, 1913.

Application filed June 21, 1912. SerialNo. 705,034.

Be it known that. we, ALBERT C. GOWING and MLLLARD C. SPENCER, both citizens of the United States, and residents of Worcester, in the county of Worcester and State of Massachusetts,have invented a new and Improved Loose-Coupled Tuning-Coil, of which-the following is afull, clear, and exact description. 7

Our invention relates to a tuning coil of the-loose coupled type to be used in wireless telegraphy and ot er arts involving the propagation of electric waves through space.

It consists of primary and secondary windings, the primary comprising two sections which can beindependently adjusted with regardto. each other, and the secondary likewise comprising twosectionswhich are capable of independent adjustment, so that the self-inductance of both the primary and secondary windings can be regulated at will,

and, at the same'timejthe mutual inductive effect of one winding upon the other can also be controlled with the utmost nicety.

Reference is to be had to the accompanying drawings, forming a part of this specification, in which similar characters of reference indicate corresponding parts in all the figures, and in which- Figure 1 is a front elevation of our improved tuning' coil; Fig. 2 is a vertical sectional view on the line 2-2 of Fig. 1, and Fig. 3 is a view showing an arrangement of circuits to illustrate how our tuning coil can be changed from the loose coupled to the close coupled type, so that it may be used for listening in on any wireless out fit in use.

Referring particularly to the drawings, the numeral 1 represents a supporting rodcarried upon standards 2 having bearings 3, This rod is referably fixed in the bearings 3., so as to old the same against rotation and on the same are, mounted a plurality of rings shown at 4;, 5, 6 and .7. The last-named ring, 7, is preferably fixed on the support ing rod 1, the other three rings being r0- tatably mounted upon the same, so that they can be shifted through any angular distance.

Each of the. rings is-not cylindrical in shape, but preferably the outer faces of the same are concentrically curved around the rod 1 as a center, making said rings similar to the spherical zone in shape. As shown in Fig. 1, the rod on which these rings are mounted is diametrically located with re-. spect to. each of them and passes through the body of each ring at opposite points.

Around the rings 4 and 5 are wound the sections constituting the portions of the primary winding, the ring 4 receiving turns forming one primary section and the ring 5 receiving a like number of turns forming the other primary section, these two sections being connected in series. The ring 6 likewise receives a number oft-urns to form one section of the secondary and the ring 7 receives the other section of the secondary, the two sections being connected together in series the same as the case of the primary winding. The primary windings are indi cated as a whole by the numeral 8 and the secondary windings by the numeml 9. On

accountof the fact that the rings 4, 5 and 6 pan be rotated around the rod 1 as an axis independently ofone another, ever possible position of adjustment can be 0 tained.

It is well lmown that in electric-wave work, the length of the wave in the circuit bears a certain relatiorito the inductance of the same, and intuning, theinductance of the receiving circuit must be regulated before any message can be received. This is, ordinarily done by cutting out a plurality of turns of the inductance coil, but with our invention we vary the inductance of the primary circuit by changing the angle at which the rings 4 and 5 arev arranged to each other. I When the rings lie in the same plane but oppose one another, the self-inductance is at a minimum, and, in efl'ect, a non-inductive winding is secured. When the rings 4 and 5 are turned to move through one hundred and eighty degrees with respect to each other, so that they no longer oppose each other, the inductance is brought upto the maximum. The same effect is obtained witl the secondary sections on the rings 6 and; 7, and the coeiiiciency of coupling of the tuner, that is, the mutual inductive effect of the primary upon the secondary winding is varied and controlled by turning the primary at any required angle to the secondary. The advantage of this improved form of tuner is that there are no sliding contacts along the wire as in the ordinary variable inductance tuning coil, also, all of the wire in our tuner is in use all of the time. There are no turns which are out out of the coil, and thus the end effect due to the inductance of the inactive coils in the ordinary tuner, is eliminated.

We also, by dispensing with the sliding contacts, eliminate the contact resistance caused by the interposition of the slider that is used with an ordinary variable inductance coil. This contact resistance consumes a large amount of'energyiand is a decided disadvantage. Furthermore, in the ordinary inductance coil which is operated by cutting out one or more turns, the smallest increment or decrement of inductance is a single turn of wire. With our coil the inductance can be variedfrom minimum to maximum by infinitely small amounts depending, of course, upon the angle betw en the planes of the rings on which the sections of the primary and secondary windings are mounted.

Furthermore, we can use stranded wire in winding the coils since there are no sliding wire contacts, and the resistance'to high frequency current is thus made less because the skin effect is eliminated, and by lessening the resistance of the primary circuit by the use of stranded wire, closer tuning can readily be obtained.

The connections shown on Fig. 3 illustrate how we can change our tuner over to a close-coupled type when listening in is to be attempted. In this view, 10 represents an aerial to which the primary turns 8 are connected in series, being grounded at 11. 12 represents a conductor in parallel with the primary turns leading to a switch 13 which bridges a gap between the conductor 12 and a contact 1 1. From this contact 14 leads a conductor-15 to the secondary 9, and from the other end of the secondary runs a conductor 18 to a switch 19, a detector 16 and a condenser 17 being interposed in this conductor 18. The switch 19 bridges the gap to a contact 20 which is connected to the wire which grounds the primary.

It is well known that a close, coupled tuner is better ada ted for picking up stations on account ot the fact that it is less selective than a loose coupled one; hence, the

use of both close and loose coupled coils may be done away with by the use with our tuner of a circuit such as shown in Fig. 3, to enable either the loose coupled or the close coupled effect to be obtained. When the switch is in the position shown in Fig. 3, the sections of the primary and secondary windings are con nected in loose coupled relation; when the switch is moved to. the dotted-lined position, the coils are in close coupled relation, and in this latter position, the operator can listen in whenever he desires Any convenient or preferred mechanism may be connected to the movable rings i, 5 and (3, so that they may be turned at will according to the degree of adjustment required and held in any desired position.

Having thus described our invention, we claim as new and desire to secure by Letters Patent:

1. In an improvement of the kind described, the combination of fourconcentric rings, a rod upon which said rings are mounted, said rod being diametrically located with respect to said rings, one of said rings being ailixed to said rod and the remainder of said rings being rotatable with respect thereto, a section of wire wound upon each outer face of two of said movable rings, said sections being connected in series to form a primary circuit, and a section of wire wound upon the outer face of each of the remaining rings and connected in series to form a secondary circuit, the adjustment of the movable rings around the rod serving to vary the self-inductive effect of the windings and the coupling of the primary and the secondary.

2. In an improvement of the kind described, the combination of four concentric rings, a rod upon which said rings are mounted, said rod bein diametrically located with respect to said rings, the innermost ofsaid rings being affixed to said rod and the remainder of said rings being rotatable with respect thereto, a section of wire wound upon each outer face of two of said movable rings, said sections being connected in series to .form a primarycircuit, and a section of wire wound upon the outer face of each of the remaining rings and connected in series to form a secondary circuit,

the adjustment of the movable rings around the rod serving to vary the self-inductive effect of the windings and the coupling ofthe primary and the secondary.

3. In an improvement of the kind described, the combination of four concentric rings, a rod upon which said rings are mounted, said rod being diametrically located with respect to said rings, the innermost of said rings being fixed to the rod and the remainder of the rings being adjustable with respect thereto, a section of wire wound upon the outer face of the inner two of said movable rings, said sect-ions being connected in series to form a primary circuit, and a section of wire wound upon the outer face of each of: the two remaining rings and connected in series to form a secondary circuit, the adjustment of the movable rings around the rod serving to vary the self-inductive eitect of the windings and the coupling of the primary and the secondary.

In an improvement of the kind described, the combination of a plurality of rings, a rod upon which said rings are mounted, one of said rings being fixed to the rod and the remainder of said rings be ing rotatable thereon, a section of wire mounted upon each of some of the movable rings and connected together to form a primary circuit, and a section of wire wound upon each of the remainder of said rings concentric rings, a rod upon which said rings are mounted, the innermost of said.

and connected to form a secondary circuit, the adjustment of the movable rings around the rod serving to vary the inductive efiect of the windings and the coupling of the primary and secondary.

. '5. In an improvement of the kind described, the combination of a plurality of rings being fixed to the rod and the remainder of said .rings movable thereon, a section of wire wound uponeach of some of said r ngs and connected to form a primary circuit, and a section of wire wound upon each oftheremainder of the rings and connected to form a secondary circuit, the adj'ustment of said serving to vary the self-inductive efiect of the windings and the coupling of the primary and secondary.

6. In a tuning coil, the combinationof a plurality of rings, primary windings each mounted, upon one of said rings, saidprimary windings being connected in'series with each other, secondary windings mount-.

ed upon others of said rings, said secondary windings being-in series with each other, andv a rod extending diametrically through each of said rings for facilitating the rotation of any of said rings relatively to the vothers.

In testimony whereof we have'signed our 'names to this specification in the presence 

